E.R,

>Yes, AutoPostBack is set to true on the drop-down list.
>
>Yes, the DetailsView is bound to an ObjectDataSource. The ObjectDataSource is using the drop-down list SelectedValue as a parameter passed to Patient.GetPatientById(int patientId) which retuns a List. I've stepped through the code to confirm that the correct PatientEntity is being added to the List
>
>Here's the SelectedIndexChanged eventhandler
> protected void ddlPatients_SelectedIndexChanged(object sender, EventArgs e)
> {
> ObjectDataSource1.DataBind();
> PatientDetailsView.DataBind();
>
> }

Did you set the UpdatePanel's UpdateMode to "Always"?

Best Regards,

Kevin McNeish
Eight-Time .NET MVP
VFP and iOS Author, Speaker & Trainer
Oak Leaf Enterprises, Inc.
Chief Architect, MM Framework
http://www.oakleafsd.com